/Engine/Source/Runtime/ApplicationCore/Public/GenericPlatform/Accessibility/GenericAccessibleInterfaces.h
Finds the deepest accessible widget in the hierarchy at the specified coordinates. The window may return a pointer to itself in the case where there are no accessible children at the position. This could return nullptr in the case where the coordinates are outside the window bounds.
The deepest widget in the UI heirarchy at X,Y
[TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [IAccessibleWidget](API\Runtime\ApplicationCore\GenericPlatform\Accessibility\IAccessibleWidget) > GetChildAtPosition ( int32 X, int32 Y )